A drive train collectively refers to a plurality of devices for transmitting energy produced in an engine to drive wheels, and is formed with various devices such as an engine, a clutch, a flywheel, a transmission, a torque converter, a damper, a drive shaft, a propeller shaft, a differential gear, and drive wheels. In a drive train testing system, the drive train as described above or a constituent device thereof is used as a test piece, a torque which is produced with a motor is input to the test piece instead of an actual engine and thus the durability, the quality and the like thereof are evaluated.
In the actual engine, the reciprocation motion of a piston within each cylinder is converted into the rotation motion of a crankshaft, and here, a periodical torque variation caused in the combustion step of each cylinder is produced. Hence, in the drive train testing system, a direct-current signal, a predetermined vibration frequency and an alternating-current signal of a vibration amplitude for drive under predetermined acceleration and deceleration are combined together so as to generate a torque command signal, and this torque command signal is input to an inverter of the motor (see, for example, Patent Document 1). In this way, in the drive train testing system, a test of the test piece is performed in an environment simulating the actual engine.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2014-215253